--- /dev/null
+/*
+ * usnjrnl.h - Defines for NTFS kernel transaction log ($UsnJrnl) handling.
+ * Part of the Linux-NTFS project.
+ *
+ * Copyright (c) 2005 Anton Altaparmakov
+ *
+ * This program/include file is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program/include file is distributed in the hope that it will be
+ * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (in the main directory of the Linux-NTFS
+ * distribution in the file COPYING); if not, write to the Free Software
+ * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifndef _LINUX_NTFS_USNJRNL_H
+#define _LINUX_NTFS_USNJRNL_H
+
+#ifdef NTFS_RW
+
+#include "types.h"
+#include "endian.h"
+#include "layout.h"
+#include "volume.h"
+
+/*
+ * Transaction log ($UsnJrnl) organization:
+ *
+ * The transaction log records whenever a file is modified in any way. So for
+ * example it will record that file "blah" was written to at a particular time
+ * but not what was written. If will record that a file was deleted or
+ * created, that a file was truncated, etc. See below for all the reason
+ * codes used.
+ *
+ * The transaction log is in the $Extend directory which is in the root
+ * directory of each volume. If it is not present it means transaction
+ * logging is disabled. If it is present it means transaction logging is
+ * either enabled or in the process of being disabled in which case we can
+ * ignore it as it will go away as soon as Windows gets its hands on it.
+ *
+ * To determine whether the transaction logging is enabled or in the process
+ * of being disabled, need to check the volume flags in the
+ * $VOLUME_INFORMATION attribute in the $Volume system file (which is present
+ * in the root directory and has a fixed mft record number, see layout.h).
+ * If the flag VOLUME_DELETE_USN_UNDERWAY is set it means the transaction log
+ * is in the process of being disabled and if this flag is clear it means the
+ * transaction log is enabled.
+ *
+ * The transaction log consists of two parts; the $DATA/$Max attribute as well
+ * as the $DATA/$J attribute. $Max is a header describing the transaction
+ * log whilst $J is the transaction log data itself as a sequence of variable
+ * sized USN_RECORDs (see below for all the structures).
+ *
+ * We do not care about transaction logging at this point in time but we still
+ * need to let windows know that the transaction log is out of date. To do
+ * this we need to stamp the transaction log. This involves setting the
+ * lowest_valid_usn field in the $DATA/$Max attribute to the usn to be used
+ * for the next added USN_RECORD to the $DATA/$J attribute as well as
+ * generating a new journal_id in $DATA/$Max.
+ *
+ * The journal_id is as of the current version (2.0) of the transaction log
+ * simply the 64-bit timestamp of when the journal was either created or last
+ * stamped.
+ *
+ * To determine the next usn there are two ways. The first is to parse
+ * $DATA/$J and to find the last USN_RECORD in it and to add its record_length
+ * to its usn (which is the byte offset in the $DATA/$J attribute). The
+ * second is simply to take the data size of the attribute. Since the usns
+ * are simply byte offsets into $DATA/$J, this is exactly the next usn. For
+ * obvious reasons we use the second method as it is much simpler and faster.
+ *
+ * As an aside, note that to actually disable the transaction log, one would
+ * need to set the VOLUME_DELETE_USN_UNDERWAY flag (see above), then go
+ * through all the mft records on the volume and set the usn field in their
+ * $STANDARD_INFORMATION attribute to zero. Once that is done, one would need
+ * to delete the transaction log file, i.e. \$Extent\$UsnJrnl, and finally,
+ * one would need to clear the VOLUME_DELETE_USN_UNDERWAY flag.
+ *
+ * Note that if a volume is unmounted whilst the transaction log is being
+ * disabled, the process will continue the next time the volume is mounted.
+ * This is why we can safely mount read-write when we see a transaction log
+ * in the process of being deleted.
+ */
+
+/* Some $UsnJrnl related constants. */
+#define UsnJrnlMajorVer 2
+#define UsnJrnlMinorVer 0
+
+/*
+ * $DATA/$Max attribute. This is (always?) resident and has a fixed size of
+ * 32 bytes. It contains the header describing the transaction log.
+ */
+typedef struct {
+/*Ofs*/
+/* 0*/sle64 maximum_size; /* The maximum on-disk size of the $DATA/$J
+ attribute. */
+/* 8*/sle64 allocation_delta; /* Number of bytes by which to increase the
+ size of the $DATA/$J attribute. */
+/*0x10*/sle64 journal_id; /* Current id of the transaction log. */
+/*0x18*/leUSN lowest_valid_usn; /* Lowest valid usn in $DATA/$J for the
+ current journal_id. */
+/* sizeof() = 32 (0x20) bytes */
+} __attribute__ ((__packed__)) USN_HEADER;
+
+/*
+ * Reason flags (32-bit). Cumulative flags describing the change(s) to the
+ * file since it was last opened. I think the names speak for themselves but
+ * if you disagree check out the descriptions in the Linux NTFS project NTFS
+ * documentation: http://www.linux-ntfs.org/
+ */
+enum {
+ USN_REASON_DATA_OVERWRITE = cpu_to_le32(0x00000001),
+ USN_REASON_DATA_EXTEND = cpu_to_le32(0x00000002),
+ USN_REASON_DATA_TRUNCATION = cpu_to_le32(0x00000004),
+ USN_REASON_NAMED_DATA_OVERWRITE = cpu_to_le32(0x00000010),
+ USN_REASON_NAMED_DATA_EXTEND = cpu_to_le32(0x00000020),
+ USN_REASON_NAMED_DATA_TRUNCATION= cpu_to_le32(0x00000040),
+ USN_REASON_FILE_CREATE = cpu_to_le32(0x00000100),
+ USN_REASON_FILE_DELETE = cpu_to_le32(0x00000200),
+ USN_REASON_EA_CHANGE = cpu_to_le32(0x00000400),
+ USN_REASON_SECURITY_CHANGE = cpu_to_le32(0x00000800),
+ USN_REASON_RENAME_OLD_NAME = cpu_to_le32(0x00001000),
+ USN_REASON_RENAME_NEW_NAME = cpu_to_le32(0x00002000),
+ USN_REASON_INDEXABLE_CHANGE = cpu_to_le32(0x00004000),
+ USN_REASON_BASIC_INFO_CHANGE = cpu_to_le32(0x00008000),
+ USN_REASON_HARD_LINK_CHANGE = cpu_to_le32(0x00010000),
+ USN_REASON_COMPRESSION_CHANGE = cpu_to_le32(0x00020000),
+ USN_REASON_ENCRYPTION_CHANGE = cpu_to_le32(0x00040000),
+ USN_REASON_OBJECT_ID_CHANGE = cpu_to_le32(0x00080000),
+ USN_REASON_REPARSE_POINT_CHANGE = cpu_to_le32(0x00100000),
+ USN_REASON_STREAM_CHANGE = cpu_to_le32(0x00200000),
+ USN_REASON_CLOSE = cpu_to_le32(0x80000000),
+};
+
+typedef le32 USN_REASON_FLAGS;
+
+/*
+ * Source info flags (32-bit). Information about the source of the change(s)
+ * to the file. For detailed descriptions of what these mean, see the Linux
+ * NTFS project NTFS documentation:
+ * http://www.linux-ntfs.org/
+ */
+enum {
+ USN_SOURCE_DATA_MANAGEMENT = cpu_to_le32(0x00000001),
+ USN_SOURCE_AUXILIARY_DATA = cpu_to_le32(0x00000002),
+ USN_SOURCE_REPLICATION_MANAGEMENT = cpu_to_le32(0x00000004),
+};
+
+typedef le32 USN_SOURCE_INFO_FLAGS;
+
+/*
+ * $DATA/$J attribute. This is always non-resident, is marked as sparse, and
+ * is of variabled size. It consists of a sequence of variable size
+ * USN_RECORDS. The minimum allocated_size is allocation_delta as
+ * specified in $DATA/$Max. When the maximum_size specified in $DATA/$Max is
+ * exceeded by more than allocation_delta bytes, allocation_delta bytes are
+ * allocated and appended to the $DATA/$J attribute and an equal number of
+ * bytes at the beginning of the attribute are freed and made sparse. Note the
+ * making sparse only happens at volume checkpoints and hence the actual
+ * $DATA/$J size can exceed maximum_size + allocation_delta temporarily.
+ */
+typedef struct {
+/*Ofs*/
+/* 0*/le32 length; /* Byte size of this record (8-byte
+ aligned). */
+/* 4*/le16 major_ver; /* Major version of the transaction log used
+ for this record. */
+/* 6*/le16 minor_ver; /* Minor version of the transaction log used
+ for this record. */
+/* 8*/leMFT_REF mft_reference;/* The mft reference of the file (or
+ directory) described by this record. */
+/*0x10*/leMFT_REF parent_directory;/* The mft reference of the parent
+ directory of the file described by this
+ record. */
+/*0x18*/leUSN usn; /* The usn of this record. Equals the offset
+ within the $DATA/$J attribute. */
+/*0x20*/sle64 time; /* Time when this record was created. */
+/*0x28*/USN_REASON_FLAGS reason;/* Reason flags (see above). */
+/*0x2c*/USN_SOURCE_INFO_FLAGS source_info;/* Source info flags (see above). */
+/*0x30*/le32 security_id; /* File security_id copied from
+ $STANDARD_INFORMATION. */
+/*0x34*/FILE_ATTR_FLAGS file_attributes; /* File attributes copied from
+ $STANDARD_INFORMATION or $FILE_NAME (not
+ sure which). */
+/*0x38*/le16 file_name_size; /* Size of the file name in bytes. */
+/*0x3a*/le16 file_name_offset; /* Offset to the file name in bytes from the
+ start of this record. */
+/*0x3c*/ntfschar file_name[0]; /* Use when creating only. When reading use
+ file_name_offset to determine the location
+ of the name. */
+/* sizeof() = 60 (0x3c) bytes */
+} __attribute__ ((__packed__)) USN_RECORD;
+
+extern bool ntfs_stamp_usnjrnl(ntfs_volume *vol);
+
+#endif /* NTFS_RW */
+
+#endif /* _LINUX_NTFS_USNJRNL_H */
Code Review / kvmfornfv.git / blobdiff